AS 


SUBSTITUTE 


By  John  S .  Burd 
.    of   Calif.  Agr  .   Sxp.   St 
Circular  No.   203. 


UNIVERSITY    OF    CALIFORNIA     AGRICULTURAL   EXPERIMENT  STATION 
COLLEGE   OF  AGRICULTURE  "c^oT,""" UN"^!^,,  D.RCCTOP 

BERKELEY  H.    E.   VAN    NORMAN,   VICE-DIRECTOR   »NO    D»»N 


CIRCULAR  No.  203  ^L  ( 

AUGUST,  1918 

PEAT  AS  A   MANURE  SUBSTITUTE 

BY  JOHN  S.  BURD 

(Chemist   in   Charge  of   Fertilizer   Control,   Professor  of   Agricultural   Chemistry, 
University  of  California.) 


The  present  tendency  of  soil  and  fertilizer  investigations  is  to 
emphasize  the  importance  of  materials  of  organic  origin  as  soil  amend- 
ments. The  virtue  of  such  substances  lies  partially  in  the  fact  that 
they  invariably  contain  small  proportions  of  necessary  chemical 
elements  (so-called  "plant  foods"),  but  considerable  importance  is 
also  attached  to  certain  characteristic  properties  of  the  organic  (non- 
mineral)  components.  Among  these  may  be  mentioned  their  great 
water-holding  power,  capacity  for  serving  as  nutrient  media  for  cer- 
tain beneficial  organisms  (bacteria,  molds,  etc.),  and  indirect  action 
on  the  mineral  particles  of  the  soil  or  the  soil  solution. 

Soils  of  the  humid  region  normally  contain  several  per  cent  of 
organic  matter.  The  amount  depends  upon  many  factors,  but  the 
finer  soils  (clays  and  loams)  usually  carry  more  than  do  the  coarse 
soils  (sands).  In  California  and  other  arid  sections  the  high  tempera- 
ture and  low  and  variable  moisture  content  have  the  effect  both  of 
preventing  the  accumulation  of  organic  matter  and  of  causing  it  to 
disappear  rapidly  from  cultivated  soils  of  all  kinds.  The  average 
organic  matter  content  of  arid  soils  seems  to  be  less  than  1  per  cent, 
i.e.,  from  one-half  to  one-quarter  that  of  similar  soils  of  the  humid 
region.  Additions  of  even  large  amounts  of  decaying  organic  matter 
to  arid  soils  will  only  serve  to  raise  the  amount  of  that  material  tempo- 
rarily, because  the  conditions  are  unfavorable  to  its  accumulation. 
Indeed,  if  organic  matter  is  to  be  effective  the  material  must  decay 
and  thus  disappear  from  the  soil. 

To  maintain  the  organic  matter  in  arid  soils,  therefore,  requires 
the  constant  addition  of  the  manure  of  domestic  animals,  green 
manures  or  cover  crops,  or  of  straw  or  hay  which  has  been  rendered 
unfit  for  animal  feed.  Any  kind  of  vegetative  tissue  which  is  capable 


of  decay  in  the  soil  may  be  used  but  it  is  exceedingly  doubtful  if 
materials  from  other  sources  are  worth  any  more  than  the  cost  of 
application.  This  means  that  the  farmer  should  use  such  waste 
materials  from  his  own  place  but  that  their  argicultural  value  is  too 
problematical  to  warrant  their  purchase  from  others. 

EVALUATION    OF    MANURES 

The  well  known  deficiencies  of  arid  soils  with  reference  to  organic 
matter  have  caused  our  farmers  to  search  everywhere  for  such 
material.  The  value  of  manure  as  a  soil  amendment  is  unquestioned, 
but  different  lots  may  vary  in  effectiveness  and  a  determination  of 
their  relative  values  presents  an  exceedingly  complex  and  technical 
problem.  The  whole  question  of  soil  fertility  is  involved  and  farmers 
may  not  hope  in  the  present  state  of  our  knowledge  to  obtain  exact 
statements  as  to  the  commercial  value  of  a  given  lot  of  manure.  The 
following  principles  are  suggested  as  the  proper  basis  for  purchasing 
farmyard  manure. 

1.  Whenever  possible  buy  on  a  basis  of  the  organic  content  of  the 
material. 

2.  If  several  lots  of  manure  are  procurable  at  different  prices,  the 
cheapest  "buy"  may  be  determined  by  dividing  the  price  per  ton  by 
the  percentage  of  organic  matter  (i.e.,  the  price  per  unit  of  organic 
matter). 

3.  The  nitrogen  content  of  the  manure  may  be  ignored  because 
the  nitrogen  will  vary  with  the  organic  content  within  sufficiently 
narrow  limits  for  this  purpose. 

4.  Ignore  the  phosphoric  acid  and  potash  of  the  manure  because 
the  former  is  usually  insignificant  and  the  latter  is  relatively  unim- 
portant as  a  fertilizer  on  California  soils. 

5.  Considerable  variation  in  the  amount  of  added  straw  in  manure 
is  permissible  as  dry  straw  contains  more  organic  matter  than  fresh 
manure. 

6.  The  amount  of  water  and  sand  or  stones  is  not  material  if  the 
manure  is  purchased  on  the  unit  basis  for  organic  matter,  except  that 
it  increases  the  transportation  charges. 

7.  A  limited  amount  of  sawdust  or  shavings  in  manure  is  to  be 
regarded  as  legitimate,  but  manures  containing  excessive   amounts 
should  be  rejected. 

8.  Manures  containing  sticks  or  visible  woody  material  other  than 
sawdust  or  shavings  should  be  rejected  even  if  offered  at  a  lower  price. 

We  are  well  aware  that  there  are  certain  very  practical  obstacles 
to  the  purchase  of  manures  on  the  unit  basis  of  organic  matter.  A 


strict  regard  for  the  other  principles  outlined  will,  however,  if  com- 
bined with  a  little  common  sense  and  experience  enable  anyone  to  buy 
as  effectively  as  the  market  conditions  permit.  Chemical  analyses 
for  nitrogen,  phosphoric  acid  and  potash  are  of  minor  value  and 
constitute  an  unnecessary  expense  or  actual  waste  of  time  on  the  part 
of  the  Experiment  Station.  Such  analyses  will  ordinarily  be  refused. 

HUMUS   VERSUS   TOTAL   ORGANIC    MATTER 

A  great  deal  of  loose  talk  is  heard  with  reference  to  humus  in  the 
soil.  If  by  humus  is  meant  organic  matter  of  vegetable  origin  capable 
of  decay  under  the  conditions  existing  in  normal  soils,  the  use  of  the 
term  is  perhaps  legitimate.  The  term  humus,  however,  is  ordinarily 
applied  to  that  portion  of  any  material  of  organic  origin  which  is 
soluble  in  dilute  alkalies.  The  use  of  the  term  in  this  sense  was  quite 
common  a  few  years  ago.  It  is,  however,  now  generally  recognized 
that  the  humus  determination  in  soils  and  soil  amendments  is  abso- 
lutely worthless  as  an  indicator  of  fertility  or  fertilizing  value.  The 
reason  for  this  is  that  solubility  in  alkali  affords  no  guaranty  that 
any  portion  of  the  material  so  dissolved  will  decay  in  the  soil;  fur- 
thermore organic  matter  which  is  not  soluble  in  alkalies  may  decay 
and  be  a  valuable  addition  to  the  soil. 

The  well  known  defects  of  the  humus  determination  and  the 
conviction  that  it  has  no  meaning  in  terms  of  soil  fertility  lead  us 
to  urge  the  abandonment  of  the  use  of  this  term.  Farmers  should 
therefore  purchase  manures  or  manure  substitutes  without  regard  to 
humus  content,  but  with  strict  regard  to  the  probable  total  of  organic 
matter. 

CONCENTRATED  MANURE,  HUMUS  AND  PEAT 

The  term  manure,  as  used  in  this  country,  is  confined  to  the  excre- 
ments of  domestic  animals  more  or  less  mixed  with  bedding  material. 
Concentrated  manure  should  only  be  used  with  reference  to  manure 
which  has  been  dried.  The  use  of  the  term  manure  or  concentrated 
manure  when  applied  to  substitutes  of  other  origin  is  fraudulent. 
For  the  reasons  indicated  heretofore  any  representation  put  fortli 
in  attempts  to  sell  any  substance  which  includes  a  statement  that 
the  material  contains  a  definite  percentage  of  humus  is  either  fraud- 
ulent in  its  intent  or  based  on  ignorance  of  the  present  status  of  the 
humus  determination. 

Deposits  of  partially  decayed  remains  of  plants  owing  their 
preservation  to  submergence  in  water  are  technically  known  as  peat. 


21 01 64 


It  is  not  legitimate  to  refer  to  such  substances  as  humus  or  concen- 
trated manure,  no  matter  how  they  have  been  treated.  Their  uses 
and  limitations  as  soil  amendments  are  set  forth  hereafter. 

PEAT  SOILS 

While  normal  soils  contain  only  a  few  per  cent  of  organic  matter, 
certain  soils  contain  very  large  proportions  of  this  material  and  the 
mineral  constituents  are  relatively  low.  This  class  comprises  muck 
and  peat  soils,  the  latter  of  which  may  contain  in  the  dry  state  80 
per  cent  or  more  of  organic  matter.  Peat  soils  owe  their  origin  to 
the  fact  that  successive  generations  of  native  plants  growing  in  stand- 
ing water  become  submerged  on  completing  their  growth  and  the 
processes  of  decay  characteristic  of  normal  soils  do  not  take  place. 
The  excess  of  water  prevents  the  access  of  air  and  acts  as  a  preserva- 
tive. In  this  manner  successive  layers  of  plant  residues  are  laid  down 
year  after  year  and  the  deposits  may  accumulate  to  a  considerable 
depth.  In  the  peat  so  derived  the  structure  of  the  plants  to  which 
they  owe  their  origin  is  still  intact  and  gives  testimony  as  to  the 
incompleteness  of  their  decomposition.  Peat  soils  may  occur  in  any 
place  where  native  growth  is  prolific  and  where  such  growth  becomes 
submerged.  They  occur  extensively  in  glaciated  regions  in  the  glacial 
ponds  or  lakes  and  also  in  marshes  and  low-lying  lands  elsewhere.  In 
the  "delta"  region  of  the  San  Joaquin  and  Sacramento  rivers  in 
California  large  areas  of  peat  lands  are  under  cultivation ;  more  limited 
areas  occur  in  other  parts  of  the  state. 

As  stated  above  large  areas  of  peat  lands  are  under  cutlivation 
and  when  properly  drained  and  free  from  disease  may  produce  excel- 
lent crops  of  barley,  potatoes,  etc.  These  soils  are  usually  highly  acid, 
even  in  the  well-drained  and  aerated  surface  soil ;  at  the  same  time 
they  frequently  contain  considerable  quantities  of  soluble  salts.  In 
common  parlance  such  soils  would  be  said  to  be  both  acid  and 
"alkaline."  There  is  this  difference  between  the  real  acidity  and  the 
so-called  "alkalinity"  that  the  acidity  does  not  seem  to  be  sufficient 
to  prevent  the  growth  of  good  crops  but  that  the  soluble  salts  tend 
to  increase  under  cultivation  and  cause  a  falling  off  in  yield  after 
several  years. 

PEAT  AS  A  SOIL  AMENDMENT 

Owing  to  the  dearth  and  high  price  of  farmyard  manure  it  is  not 
surprising  that  the  practically  inexhaustible  supply  of  peat  with  its 
high  organic  content  has  been  suggested  as  a  possible  substitute  for 
this  valuable  amendment. 


A  discussion  as  to  the  value  of  any  material  used  to  improve  the 
producing  capacity  of  a  soil  must  be  based  in  part  on  the  amount  of 
the  important  constituents  and  in  part  upon  their  so-called  avail- 
ability. It  is  evident  that  very  small  percentages  of  the  important 
constituents  in  a  fertilizer  or  amendment  cannot  have  an}'  material 
effect  in  modifying  the  composition  of  a  soil,  no  matter  how  "avail- 
able" they  may  be;  on  the  other  hand,  large  percentages  will  be 
equally  ineffective  if  of  low  availability. 

The  two  constituents  which  peat  might  be  expected  to  add  to  a 
soil  when  used  as  a  fertilizer  or  amendment  are  organic  matter  and 
nitrogen.  The  total  organic  matter  and  total  nitrogen  of  fresh  peat 
approximate  more  nearly  in  amount  to  that  of  farmyard  manure  than 
to  any  other  substance  commonly  applied  to  soils.  We  may  therefore 
logically  compare  peat  with  manure,  a  method  which  has  the  addi- 
tional advantage  of  using  as  a  standard  a  material  of  well  known 
agricultural  value. 

ANALYSES  OF  PEAT 
(Expressed  as  percentages  of  the  fresh  material") 


Water    

Surface 

1 
66.23 

Subsurface 
(drained) 
o 

68.93 

Subsurface 
(wet) 
3 

64.74 

Subsurface 
(wet) 
4 
7S.11 

Organic  matter 

18.74 

24.37 

22.28 

13.84 

Mineral    matter    (ash)  

.        la.03 

(5.70 

12.98 

8.0.1 

Total   — -     100.00  100.00  100.00  100.00 

PLANT  FOOD  CONTENT  OF  PEAT 
(Three  different  samples) 

Per  cent  1'crcent  Percent 

Nitrogen    0.61                           0.86  0.49 

Phosphoric  acid  0.16                         0.17  0.12 

Potash    0.19                          0.12  0.06 

Farmyard  manures  arc  of  variable  composition,  depending  on  the 
kind  of  animal,  age,  method  of  fetding.  amount  of  straw,  etc.  We 
may  take  as  an  average  for  fn  sh  manure  with  some  straw  about  120 
per  cent  of  organic  matter,  ().">()  per  cent  nitrogen.  ().'J.">  per  cent  phos- 
phoric acid  and  ().(>()  per  cent  potash.  The  peat  analyses  here  given 
show  that  this  material  contains  roughly  about  the  same  total  of 
organic  matter  (varying  from  considerably  less  to  slightly  more)  than 
manure;  that  the  nitrogen  content  of  both  substances  is  about  the 
same  (many  samphs  of  manure  contain  more  nitrogen  than  many 
peats);  and  finally,  that  the  peats  all  contain  much  less  phosphoric 


acid  and  potash  than  the  average  sample  of  manure.  It  is  clear  that 
even  if  it  were  true  that  the  organic  matter  of  fresh  peat  decomposes 
with  the  same  facility  as  that  of  manure  and  if  the  availability  of 
the  so-called  plant  foods  in  peats  is  equal  to  that  of  manure,  the  peat 
could  not  possibly  be  considered  as  of  equal  value  to  the  average  fresh 
manure. 

DECOMPOSABILITY    OF    PEAT 

A  peat  soil,  even  when  drained  and  aerated,  or  a  pile  of  the  same 
material,  will  maintain  its  initial  appearance  almost  indefinitely,  in 
marked  contrast  to  the  manure  pile,  in  which  fundamental  changes 
may  be  observed  from  time  to  time.  No  one  who  has  made  such 
observations  can  fail  to  be  impressed  by  the  difference  between  the 
two  substances  and  the  obvious  inertness  of  the  former.  It  is  evident 
that  such  inert  material  as  peat  is  incapable  of  the  rapid  decay  usually 
associated  with  "available"  materials  like  manure. 

Much  work  has  been  done  by  several  investigators  on  the  nitro- 
genous constituents  of  peat.  The  general  conclusion  with  reference 
thereto  may  be  epitomized  by  the  following  quotation.1  "Practically 
all  the  nitrogen  in  the  peats  is  of  organic  nature.  Through  weathering 
the  organic  nitrogenous  bodies  present  in  the  brown  peat  change  quite 
slowly." 

We  have  observed  in  this  laboratory  that  peat  from  California 
sources  is  similar  to  that  from  other  sources  referred  to  above  in  that 
its  nitrogen  consists  almost  entirely  of  organic  nitrogen  and  not  of 
the  highly  available  nitrate  and  ammonia  salts.  The  Citrus  Experi- 
ment Station  at  Riverside  has  made  similar  observations  and,  in 
addition,  nitrification  studies  which  unquestionably  demonstrate  the 
low  availability  of  peat  nitrogen.  The  conclusions  reached  in  these 
experiments  are  indicated  from  the  following  excerpt  from  a  report 
of  Dr.  W.  P.  Kelley,  Professor  of  Agricultural  Chemistry,  Citrus 
Experiment  Station,  Riverside,  California. 

. . .  After  the  above  experiments  had  stood  for  a  year  a  study  was  also  made 
of  the  effects  that  had  been  produced  on  the  solubility  of  the  various  plant  foods 
present.  The  results  showed  that  in  neither  case  had  any  appreciable  effect  been 
produced  by  the  peat.  The  manure  and  alfalfa  hay,  on  the  other  hand,  had 
notably  increased  the  solubility  of  the  various  plant  food  elements  present. 

From  the  preceding  results,  it  is  evident  that  the  peat  used  in  these  experiments 
is  an  extremely  inert  substance,  and  that  it  is  of  such  nature  as  to  be  practically 
unaffected  by  the  action  of  soil  bacteria.  The  fact  that  the  peat  produced  no 
effect  either  on  nitrification  or  dentrification,  on  the  one  hand,  or  on  the  solubility 


i  Tech.  Bull.  No.  4,  Michigan  Agr.  College,  Nov.,  1909,  p.  28,  Organic  Nitro- 
genous Compounds  in  Peat  Soils. 


of  the  plant  food  constituents  contained  in  the  soil,  on  the  other,  is  especially 
strong  evidence  in  support  of  this  view.  It  would  appear  reasonable  to  conclude, 
therefore,  that  the  chemical  and  biological  effects  produced  by  this  material,  at 
least  for  the  first  year  after  it  has  been  applied,  will  be  negligible,  and  since  the 
plant  foods  contained  in  the  peat  itself  are  largely  unavailable,  the  effects  that 
will  be  produced  on  crops  under  field  conditions,  will  probably  not  be  great. 

In  addition  to  the  above  experiments,  I  have  frequently  observed  the  conditions 
in  certain  citrus  groves  near  Kiverside  where  peat  has  been  in  use  for  some  time, 
but  as  yet  no  apparent  effects  have  been  produced  on  the  growth  or  well-being 
of  the  trees.  The  lumps  of  peat  can  still  be  seen  in  the  soil,  and  careful  exam- 
ination shows  that  it  has  not  undergone  any  apparent  change.  Ordinarily,  stable 
manure  when  applied  in  this  section  becomes  completely  decomposed  in  much  less 
time  than  has  elapsed  since  the  application  of  peat  in  the  groves  referred  to. 

In  view  of  the  well  known  experience  with  peat  in  other  parts  of  the  world, 
and  the  information  derived  from  the  above  studies  on  this  material,  it  seems 
safe  to  conclude  that  the  farmer  in  California  is  not  justified  in  placing  more  than 
a  nominal  fertilizing  value  on  this  material. 

(Signed)  W.  P.  KELLEY. 

In  the  laboratory  of  Agricultural  Chemistry  at  Berkeley  we  have 
demonstrated  that  virgin  peat  soils  gave  a  three-fold  crop  when 
fertilized  with  phosphate  fertilizers,  indicating  very  clearly  that  the 
phosphate  in  fresh  peat  is  likely  to  be  highly  unavailable.  We  have 
made  no  studies  as  to  the  availability  of  potash  in  peat,  but  as  stated 
above,  the  total  potash  is  so  small  as  to  be  negligible.  Peat  contains 
from  a  third  to  a  tenth  or  less  potash  than  the  normal  California  soil 
so  that  its  addition  would  actually  decrease  the  percentage  of  total 
potash  in  soils  on  which  it  is  used. 


CONCENTRATED  PEAT 

Peat  like  any  other  watery  material  can  be  concentrated  by  the 
simple  process  of  evaporating  the  water.  The  effect  of  this  is  to 
increase  the  amount  of  each  non-volatile  constituent  in  proportion  to 
the  loss  of  water.  The  advantage  to  be  derived  from  this  practice  is 
that  the  resulting  material  weighs  only  about  a  third  as  much  as  the 
original  peat  and  contains  about  three  times  as  much  of  each  con- 
stituent (other  than  water)  in  a  ton  of  dried  material. 

If  peat  has  any  fertilizing  value  the  drying  is  justifiable  in  that 
it  saves  about  two-thirds  of  the  transportation  charges  if  the  drying 
is  thorough.  Such  substances  tend  to  absorb  considerable  quantities 
of  moisture  from  the  air,  however,  so  that  the  proportionate  increased 
concentration  estimated  above  represents  a  maximum  figure  for  peat 
of  average  composition. 


8 

ILL   EFFECTS   OF   DRYING 

Drying  or  desiccation  of  vegetative  material  has  been  observed  to 
decrease  its  capacity  for  rapid  nitrification,  even  when  subsequently 
moistened  and  added  to  soils.2  A  portion  at  least  of  the  benefit  of 
drying  peat  may  be  lost  by  a  lowering  of  the  nitrifiability  of  the 
material. 

DRIED    PEAT    VERSUS    FARMYARD    MANURE 

The  statement  is  frequently  made  that  dried  peat  is  more  con- 
centrated than  fresh  farmyard  manure.  This  is  true  but  it  is  quite 
possible  to  dry  farmyard  manure  and  thus  obtain  a  much  more 
concentrated  product  than  dried  peat.  The  reason  for  this  is  that 
while  fresh  peat  and  fresh  farmyard  manure  contain  about  the  same 
percentages  of  organic  matter,  the  remaining  material  in  manure  is 
largely  water,  while  peat  normally  contains  much  more  of  valueless 
ash  or  mineral  ingredients  which  reduce  the*  percentage  of  organic 
matter  in  the  dried  product. 


INOCULATED   PEAT 

The  claim  is  frequently  made  that  peat  may  be  advantageously 
inoculated  with  various  organisms,  thereby  increasing  the  availability 
of  its  nitrogen  content  or  enhancing  the  nitrogen-fixing  power  of  soils 
to  which  it  is  applied.  A  very  clear  exposition  of  the  prevailing 
opinion  of  scientific  men  with  reference  to  the  possibilities  of  inoculat- 
ing peat  may  be  obtained  from  the  following  letter  from  Dr.  Chas. 
B.  Lipman,  Professor  of  Soil  Chemistrj^  and  Bacteriology,  University 
of  California. 

. . .  The  only  extensive  studies  which  have  been  made  on  the  inoculation  of 
peat  are  those  which  were  carried  out  in  England  by  Bottomley  and  his  associates 
at  the  University  of  London,  and  those  carried  out  by  Voelcker  at  the  Woburu 
Experiment  Station,  by  Kussell  and  his  associates,  at  the  Kothamsted  Experiment 
Station,  and  by  Chittenden,  both  of  which  latter  wrere  intended  to  check  the  claims 
of  Bottomley.  Mr.  Bottomley 's  claims  were  that  peat  is  very  much  improved  for 
purposes  of  soil  amendment  by  its  inoculation  with  bacteria  closely  similar  to 
many  of  the  so-called  ammonifying  or  ammonia-producing  bacteria  in  the  soil. 
The  idea  involved  is  that  the  very  inert  organic  nitrogenous  compounds  contained 
in  the  peat  are  rendered  soluble  and  easily  hydrolizable  through  the  action  of  the 
micro-organisms.  It  has  been  further  claimed  by  Bottomley  that  some  of  the 
dissolved  organic  compounds  thus  produced  may  serve  after  the  sterilization  of 
the  peat  as  markedly  efficient  sources  of  energy  for  micro-organisms  which  have 


2  Stewart,  G.  B.,  Availability  of  the  Nitrogen  in  Pacific  Coast  Kelps,  Journal 
of  Agricultural  Kesearch,  vol.  IV,  no.  1,  April,  1915. 


9 

the  power  of  fixing  nitrogen  from  the  air,  and  which  have  been  introduced  into 
such  sterilized  peat.  The  material  thus  prepared  is  commercially  known  as 
"Humogen"  or  bacterized  peat.  Bottomley  and  some  of  his  commercial  sup- 
porters have  carried  out  experiments  and  shown  photographs  of  the  plants  involved, 
which  are  calculated  to  substantiate  their  extravagant  claims  for  the  improvement 
of  the  peat  through  inoculation. 

The  other  English  experiments  which  are  referred  to  above,  however,  have 
given  little  or  no  support  to  the  claims  made  by  Bottomley.  Chittonden  and 
Russell,  in  particular,  have  gone  on  record  as  saying  that,  in  their  experiments, 
the  plants  grown  on  soils  treated  with  the  bacterized  peat  do  not  seem  to  have 
been  affected  beneficially  any  more  than  plants  grown  on  similar  soils  not  treated 
with  that  substance.  In  view  of  the  fact  that  such  careful  experimenters,  prob- 
ably among  the  most  conservative  in  the  field  of  agricultural  science,  have  made 
these  statements  renders  it  necessary  for  any  one  commenting  on  the  subject  in 
question  to  decide  that  the  public  will  be  unjustly  and  unscientifically  advised 
if  it  is  not  warned  that  many  more  experiments  by  careful  students  of  the  sub- 
ject are  necessary  before  the  exact  facts  in  the  case  can  be  ascertained.  In  view, 
therefore,  of  this  situation,  coupled  with  the  traditional  information  which  we 
have  always  had  relative  to  the  inert  nature  of  peat  and  its  ineffectiveness  when 
applied  to  soils,  make  it  necessary  for  me  to  advise  against  the  acceptance  by  the 
public  of  any  statements  made  on  the  superior  nature  of  inoculated  as  against 
uninoculated  peat,  as  well  as  on  its  value  as  a  source,  of  nitrogen  and  even  of 
organic  matter  to  soils. 

(Signed)  CHAS.  B.  LIPMAN. 


SAND  OR   SILT   IN    PEAT 

When  peat  beds  are  subjected  to  the  influence  of  rising  or  falling 
water  they  are  always  more  or  less  contaminated  with  mineral  par- 
ticles of  sand,  silt,  or  clay.  The  effect  of  this  is  to  render  the  resulting 
material  still  less  valuable  as  a  soil  amendment,  the  mineral  particles 
constituting  a  worthless  filler. 


SUMMARY 

1.  The  substances  commonly  included  in  the  term  organic,  matter 
and  derived  from  plant  or  vegetative  tissues  have  a  recognized  valut- 
as soil  amendments  apart  from  their  plant  food  contents. 

2.  Organic  matter  is  contained  in  manures  of  all  kinds,  in  straw, 
hay,  etc.,  and  in  peat. 

'}.  The  commercial  value  of  substances  of  the  same  kind,  such  as 
manures,  should  be  based  upon  their  percentages  of  organic  matter. 

4.  Fresh  peat  contains  about  the  same  amount  of  organic  matter 
as  the  average  fresli  manure. 

5.  Dried    peat    will    normally    contain    less    organic    matter    than 
manure  of  the  same  degree  of  dryness. 


10 

6.  Peat,  unlike  farmyard  manure,  does  not  decay  rapidly  in  the 
soil,  nor  is  it  readily  nitrified;  it  cannot,  therefore,  be  regarded  as  an 
' '  available ' '  material. 

7.  We  regard  the  inoculation  of  peat  as  a  useless  procedure  and 
an  unnecessary  expense  to  the  farmer. 

8.  Peat  frequently  contains  considerable  sand  or  silt,  making  it 
still  less  valuable  agriculturally. 

9.  Any  plant  substance  which  has  undergone  partial  decay  in 
water  is  to  be  regarded  as  peat. 

10.  In  the  absence  of  more  favorable  results  than  those  heretofore 
obtained  in  experiments  with  peat,  the  use  of  this  material  is  not 
advised. 

11.  Farmers  are  expressly  advised  that  the  plant  food  constituents 
of  peat  are  not  to  be  regarded  as  having  the  same  commercial  value 
as  those  of  high  grade  fertilizers  nor  is  peat  commercially  or  agri- 
culturally as  valuable  as  farmyard  manure. 


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BULLETINS 
No. 

Enological  Investigations.  274. 
Humus  in  California  Soils. 

The  Loquat.  275. 
Utilization  of  the  Nitrogen  and  Organic 

Matter   in    Septic   and    Imhoff  Tank  276. 

Sludges.  277. 

Deterioration  of  Lumber.  278. 

Irrigation   and  Soil  Conditions  in  the  279. 

Sierra  Nevada  Foothills,  California.  280. 
The  Citricola  Scale. 

New  Dosage  Tables.  281. 
Melaxuma    of    the    Walnut,    "Juglans 

regia."  282. 
Citrus   Diseases   of   Florida   and   Cuba 

Compared  with  Those  of  California.  "83. 

Size  Grades  for  Ripe  Olives.  284. 

The  Calibration  of  the  Leakage  Meter.  286. 

Cottony  Rot  of  Lemons  in  California.  288. 
A  Spotting  of  Citrus  Fruits  Due  to  the 

Action  of  Oil  Liberated  from  the  Rind.  290. 
Experiments  with  Stocks  for  Citrus. 
Growing  and  Grafting  Olive  Seedlings.  291. 
A  Comparison  of  Annual  Cropping,  Bi- 
ennial Cropping,  and  Green  Manures  292. 

on  the  Yield  of  Wheat. 

Feeding  Dairy  Calves  in  California.  293. 

Commercial  Fertilizers.  294. 

Preliminary  Report  on  Kearney  Vine-  295. 

yard  Experimental  Drain.  296. 

CIRCULARS 

No. 

Correspondence  Courses  in  Agriculture.  164. 

Increasing  the  Duty  of  Water.  165. 

Grafting  Vinifera  Vineyards. 

Alfalfa   Silage  for  Fattening  Steers.      •  166. 

Spraying  for  the  Grape  Leaf  Hopper.  167. 

House  Fumigation.  168. 

Insecticide  Formulas. 

The  Control  of  Citrus  Insects.  169. 

Spravine  for  Control  of  Walnut  Aphis.  170. 

County  Farm  Adviser. 

Official  Tests  of  Dairy  Cows.  172. 

Melilotus  Indica.  174. 

Wood  Decay  in  Orchard  Trees.  175. 

The  Silo  in  California  Agriculture. 

The   Generation   of  Hydrocyanic   Acid  176. 
Gas  in  Fumigation  by  Portable  Ma- 
chines. 177. 

The  Practical  Application  of  Improved  179. 
Methods  of  Fermentation  in  Califor- 
nia Wineries  during  1913  and  1914.  181. 

Practical  and  Inexpensive  Poultry  Ap- 
pliances. 182. 

Control    of    Grasshoppers   in    Imperial 

Valley.  183. 

Oidium  or  Powderv  Mildew  of  the  Vine.  184. 

Tomato  Growing  in  California.  186. 

"Lungworms."  1-87. 

Round  Worms  in  Poultry.  188. 

Feedine  and  Management  of  Hogs.  189. 

Some  Observations  on  the  Bulk  Hand-  J91. 

ling  of  Grain  in  California.  192. 

Announcement  of  the  California  State  193. 

Dairy  Cow  Competition,   1916-18.  196. 

Irrigation   Practice  in   Growing  Small  197. 
Fruits  in  California. 

Bovine  Tuberculosis.  198. 

How  to  Operate  an  Incubator.  200. 

Control  of  the  Pear  Scab. 

Home  and  Farm  Canning.  201. 

Lettuce  Growing  in  California.  202. 

Potatoes  in  California. 

White    Diarrhoea    and    Cocoidiosis    of 
Chicks. 


The  Common  Honey  Bee  as  an  Agent 
in  Prune  Pollination. 

The  Cultivation  of  Belladonna  in  Cali- 
fornia. 

The  Pomegranate. 

Sudan  Grass. 

Grain  Sorghums. 

Irrigation  of  Rice  in  California. 

Irrigation  of  Alfalfa  in  the  Sacramento 
Valley. 

Control  of  the  Pockei  Gophers  in  Cali- 
fornia. 

Trials  with  California  Silage  Crops  for 
Dairy  Cows. 

The  Olive  Insects  of  California. 

Irrigation  of  Alfalfa  in  Imperial  Valley. 

Commercial  Fertilizers. 

Potash  from  Tule  and  the  Fertilizer 
Value  of  Certain  Marsh  Plants. 

The  June  Drop  of  Washington  Navel 
Oranges. 

The  Common  Honey  Bee  as  an  Agent 
in  Prune  Pollination.  (2nd  report.) 

Green  Manure  Crops  in  Southern  Cali- 
fornia. 

Sweet  Sorghums  for  Forage. 

Bean  Culture  in  California. 

Fire  Protection  for  Grain  Fields. 

Topping  and  Pinching  Vines. 


Small  Fruit  Culture  in  California. 
Fundamentals   of    Sugar    Beets   under 

California   Conditions. 
The  County  Farm  Bureau. 
Feeding  Stuffs  of  Minor  Importance. 
Spraying  for  the  Control  of  Wild  Morn- 

ing-Glory  within  the  Fog  Belt. 
The  1918  Grain  Crop. 
Fertilizing     California     Soils    for     the 

1918  Crop. 
Wheat  Culture. 
Farm  Drainage  Methods. 
Progress  Report  on  the  Marketing  and 

Distribution  of  Milk. 
Hog     Cholera      Prevention     and     the 

Serum  Treatment. 
Grain  Sorghums. 
Factors   of    Importance    in    Producing 

Milk  of  Low  Bacterial  Count. 
Control     of     the     California     Ground 

Squirrel. 
Extending  the  Area  of  Irrigated  Wheat 

in  California  for  1918. 
Infectious  Abortion  in  Oows. 
A  Flock  of  Sheen  on  the  Farm. 
Poultry  on  the  Farm. 
Utilizing  the  Sorghums. 
Lambing  Sheds. 
Winter  Forage  Crops. 
Pruning  the  Seedless  Grapes. 
Cotton  in  the  San  Joaquln  Valley. 
A  Study  of  Farm  Labor  in  California. 
Dairy  Calves  for  Veal. 
Suggestions   for   Increasing   Egg   Pro- 
duction in  a  Time  of  High-Feed  Prices. 
Syrup  from  Sweet  Sorehnm 
Growing  the  Fall   or   Second   Crop  of 

Potatoes  in  California. 
Helpful  Hints  to  Hog  Raisers. 
County    Organization    for    Rural    Fire 

Control. 


UNIVERSITY  of  CALIFORNIA' 


S661      Burd  - 
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